Cattle have 60 chromosomes in somatic cells. Determine the number of chromosomes and DNA molecules in ovarian cells in the interphase before division and after division of meiosis I. Explain how such a number of chromosomes and DNA molecules are formed.
In the interphase before the start of division, the number of DNA molecules is 120, the number of chromosomes is 60; after meiosis I, the number of chromosomes – 30, DNA – 60. Before division, DNA molecules double, their number increases, but the number of chromosomes does not change – 60, each chromosome consists of two sister chromatids. Meiosis I is a reduction division, so the number of chromosomes and DNA molecules is halved.
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